A privacy-preserving cross-chain cryptocurrency transfer scheme based on commitment scheme and zero-knowledge proof

The demand for cross-chain transactions is increasing with the emergence of different types of cryptocurrencies. Most of solutions require cross-chain transaction information to be collected publicly, which undermines the privacy of cross-chain payers. To address this challenge, we propose a privacy-preserving scheme for cross-chain cryptocurrency transactions, which prevents any party from accessing the full transaction details of the payers. Based on the commitment scheme, we first construct a privacy-preserving cryptocurrency lock and release protocol for issuing or redeeming mapped cryptocurrencies in smart contracts. We then propose a mapped cryptocurrency confidential transaction scheme (MCCT) based on zk-SNARK and design an atomic exchange protocol based on it. We analyze the security of our scheme and implement it with smart contracts on an Ethereum test network. The experimental results demonstrate that for 100 exchanges, the additional time cost of our proposed solution is approximately 39% compared to the existing solution, which is considered acceptable.